Over the past few decades, localization devices and methods have traditionally relied upon global positioning systems (GPS). These ubiquitous global navigation satellite systems provide an adequate estimate of location in most areas around the world. However, GPS localization is not infallible, and as a result there are many locations where the signals are not sufficiently detected to allow for localization.
For example, transmissions from GPS satellites are often blocked by buildings in city settings, by landscape and trees in outdoor settings, and by the earth in subway systems or other transportation systems. Perhaps the most common interference with GPS localization occurs inside buildings where satellite reception is inadequate. In each of these conditions, there is a demand for adequate localization techniques.
Accordingly, there is a continued need in the art for localization methods and systems that work in settings where localization techniques such as GPS are not available.